1. Field of the Invention
The present invention relates to a water-based ink for ink-jet recording and an ink cartridge.
2. Description of the Related Art
There has been suggested that a water-based pigment ink contains water dispersible polymer in order to improve optical density (OD value). Such a water-based pigment ink is disclosed, for example, in Japanese Patent Application Laid-open No. 2006-2141 and Japanese Patent Application Laid-open No. 2012-87309.
However, the water-based pigment ink containing the water dispersible polymer has such a problem that using the water dispersible polymer increases the viscosity of the water-based pigment ink to cause discharge failure easily. In view of this, an object of the present teaching is to provide a water-based pigment ink for ink-jet recording which can satisfy both improved optical density (OD value) and an excellent discharge property.